The invention relates to a workpiece feeding apparatus, especially for machining equipment in a continuous operation by moving a workpiece through a feeding channel which includes adjustably supported workpiece guide means.
Large machines for production working of the surfaces of wood and wood material boards, veneered panels, polyester varnish coatings, felt and foam rubber workpieces, metals, and cast or natural stone slabs are well-known. The workpiece moves or is moved on conveying means through these machines whereby guide means such as pressure feed rollers press on the top surface of the workpiece while its downwardly facing surface is being worked as is the case, for example, in conventional so called bottom sanding machines, especially of the wide belt type. If the workpiece is being worked on its top surface pressure is applied by a support table, usually in the form of a conveyer, as is the case in so called top sanding machines, wherein pressure bars or counter pressure rollers arranged adjacent to the machining station form together with the conveyer table the necessary guide means for the workpiece.
If the workpieces are to move through their feeding channel of the apparatus without trouble, the guide means or at least a portion of the guide means must be adjusted for variations in the dimensions of the workpieces, especially with regard to workpiece thickness in order to provide the pressure with which the workpiece must be forced against the tool such as a wide width sanding belt. Adjustments by known manual or servomotor means involve moving either the guide or working components perpendicularly relative to the workpiece. Such prior art adjustment means, however, require that an operator first ascertains the thickness of the workpiece, for example, by means of a caliper rule or a dial gauge before he can go ahead with the adjustment. This procedure is not only time consuming but also subject to measuring errors. Thus, the rate of rejections is particularly high when the workpiece dimensions change frequently.